Leak detection apparatus

Abstract

A system for detecting a leak in a line consists of an apparatus for detecting a drop to a predetermined pressure in the line; and, once the predetermined pressure is reached, an output is developed by the pressure-sensing apparatus. A bi-state circuit responsive to the output from the detecting apparatus has a first state when no leak is present and a second state when the predetermined pressure is detected. A switching circuit has its input connected through the bi-state circuit. A timing circuit develops a signal at its output after a predetermined time and applies this signal to a bi-state gate circuit. A nonleak detector is coupled to the output of the bi-stable gate circuit to indicate that no leak is present in the system. When the bi-state circuit receives an indication from the detector apparatus that the predetermined pressure has been reached, the bi-state circuit prevents the development of the output signal from the timer circuit and operates an indicator means which indicates that a leak has been detected. The leak detection apparatus is reset on a periodic basis.

What I claim is: 
     
       1. A leak detection device for a system under pressure comprising: a. means for detecting a predetermined pressure;   b. a bi-state means responsive to said detecting means having a first state when no leak is present and having a second state when a predetermined pressure is detected;   c. switch means having its input connected through said bi-state means;   d. timing means having a signal at its output after a predetermined period of time;   e. bi-stable gate means having its input connected to said timing means output;   f. a nonleak indicator means coupled to the output of said bi-stable gate means to indicate that no leak is present in the system;   g. means responsive to said second state coupled to said timing circuit and said switch means to eliminate said time output signal to said bi-state gate means and operate said switching means;   h. an indicator means coupled to said switching means to indicate that a leak has been detected; and   i. means for resetting said bi-stable gate.   
     
     
       2. A circuit for a leak detecting system having a pressure-sensing apparatus and an output circuit responsive to a predetermined pressure, said circuit comprising: a. an input;   b. switching means connected to said input;   c. a timer means generating an output signal after a predetermined interval of time;   d. bi-stable switch means having an input and an output circuit;   e. means for applying the output signal from said timer means to the input of said switch means for closing its output upon receiving said timing signal;   f. a nonleak indicator means connected to the output of said bi-stable output circuit for operating said indicator when said output circuit is closed;   g. leak indicator means connected to said switch means;   h. means for connecting said timer to said pressure-sensing apparatus output for terminating the output signal from said timer and for closing said switching means to operate said leak indicator means; and   i. means for resetting said circuit.   
     
     
       3. A circuit as described in claim 2 wherein said timer means comprises a unijunction transistor having first and second bases and an emitter; means for applying power to said first and second bases and through a resistor to ground; and through an R-C network to said emitter. 
     
     
       4. A circuit as described in claim 2 wherein said bi-stable switch means comprises a silicon-controlled rectifier having an anode, a cathode, and a gate, and wherein said cathode and anode are connected in series with a power source and said nonleak indicating means, and said gate is connected to receive the output signal from said timer circuit means. 
     
     
       5. A circuit as described in claim 2 wherein said switch means comprises a first and second transistor having a base collector and emitter, said first transmitter having its base connected to said input and its emitter connected to said leak indicator means and to the base of said second transister and its collector connected to the means for connecting said timer to said pressure-sensing apparatus output. 
     
     
       6. A leak detection circuit for a system having a pressure-sensing apparatus and an output circuit responsive to a predetermined pressure, said circuit comprising: a. power means having a ground;   b. a unijunction timing circuit having a first and second base and an emitter;   c. R-C timing interval means connected between said source of power and said emiter;   d. an output means connected from said first base to ground;   e. an R-C time contact means connected from said power means to said base and to said ground;   f. a gated switching circuit having an input, output, and gate;   g. a nonleak indicating means connected from a source of power through the input and output of said gated circuit to ground;   h. a leak indicating means connected from ground through the emitter to collector of a first transistor to a source of power and means for connecting the base of said first transistor through said output circuit to a source of power; and   i. a second transistor having means connecting its base to the emitter of said first transistor means for connecting its emitter to ground and means for connecting its collector to the emitter of said unijunction timing transistor.